Alkanes

• Alkanes are hydrocarbons that contain only single bonds and are thus classified as saturated compounds.
• They follow the general formula CnH2n+2.
• These compound form a homologous series, meaning that each successive member differs by a CH2 unit.
• The first four alkanes are methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10).
• Alkanes are non-polar due to the small difference in electronegativity between carbon and hydrogen atoms, hence they have weak Van der Waals’ forces.
• These molecules demonstrate a trend in physical properties; as molecular size increases, boiling point, melting point and density increase.
• Alkanes are relatively unreactive (inert) due to the strength of their carbon-hydrogen bonds.
• However, they will combust in a plentiful supply of oxygen to produce carbon dioxide and water vapour.
• The process of converting alkanes into alkenes and hydrogen is known as ‘cracking’.
• In terms of isomerism, alkanes display chain and position isomerism. As the number of carbon atoms increase, so do the number of possible isomers.
• Alkanes can be produced from crude oil through a process called fractional distillation which makes use of their alternating boiling points.
• Alkanes can react with halogens in the presence of UV light or heat. The reaction proceeds via free radical substitution.